Biofouling is a major challenge in engineering applications, especially in the marine sector. Marine biofouling is defined as a undesirable accumulation of macromolecular compounds, and micro- and microorganisms on submerged surfaces that can affect the functionality of subsea equipment and consequently lead to dramatic economic and ecological impacts when operating underwater [1].

To combat biofouling in the marine sector, coatings containing chemically active compounds such as silver, copper, and tributyltin (TBT) have been widely used. However, these agents lack specificity and present high toxicity to non-target marine organisms [2, 3]. Therefore, harmful coating compounds are increasingly banned worldwide, resulting in an urgent need for non-toxic alternatives.

In this study, we demonstrate a potential way to reduce biofouling using laser-based surface texturing. In the first step, we used a 300-fs laser system to generate nano- and microstructures on titanium plates to affect the surface topography. Next, we tailored the surface chemistry and wetting using three different post-treatments (boiling in pure water, heating in air, and salinization). The modified plates were then incubated in the Baltic Sea for two weeks, and microbial and algal biomass was quantified by measuring dry biomass of fouling mats. Additionally, DAPI staining was used to estimate cell numbers, and fluorescence in situ hybridization (FISH) was employed to classify cells within the biofilm as part of a 16S rRNA-based approach.

The results show that laser-induced microstructures can significantly reduce biofilm formation compared to smooth reference plates. Furthermore, biomass, cell numbers and cultivation indicate a potential supplemental antifouling effect of post-treating samples by heating in air and boiling in water. However, titanium plates with micro-scale structures show lower biomass than reference and nanostructured plates, regardless of the wetting state and post-treatment. This suggests that the micro-scaled surface potentially inhibits microbial growth.

Since surface texturing using laser sources presents a harmless alternative to toxic coatings and a scalable processing method, we are engaged to perform further investigations to confirm and establish this approach to face biofilm formation.

References

1. Jin H, Wang J, Tian L et al. (2022) Recent advances in emerging integrated antifouling and anticorrosion coatings. Materials & Design 213:110307. https://doi.org/10.1016/j.matdes.2021.110307

2. Jin H, Tian L, Bing W et al. (2022) Bioinspired marine antifouling coatings: Status, prospects, and future. Progress in Materials Science 124:100889. https://doi.org/10.1016/j.pmatsci.2021.100889

3. Amara I, Miled W, Slama RB et al. (2018) Antifouling processes and toxicity effects of antifouling paints on marine environment. A review. Environmental Toxicology and Pharmacology 57:115–130. https://doi.org/10.1016/j.etap.2017.12.001